WEST POINT, Pa. -(Dow Jones)- Merck & Co. (MRK) officials are cautiously hopeful that the shingles vaccine Zostavax will finally live up to its market potential after several years of manufacturing problems that limited the shot's supply.

The Whitehouse Station, N.J., pharmaceutical company has restored supply of Zostavax to the point where it has filled customer back orders. Last week, Merck began running U.S. television commercials aimed at raising awareness of shingles, a sometimes-painful skin and nerve condition that's triggered by the same virus that causes chickenpox.